This invention relates to a mounting system for mounting electrical modules to a rail in a stacked arrangement.
It is well known in the art to use a plurality of electrical input/output modules that fit together in a stacked arrangement and are electrically connected together. It is also known that the modules may be mounted to a U-shaped metal rail that supports the device and provides electrical connection to ground.
U.S. Pat. No. 5,775,955 discloses one such arrangement in which each module has plug-compatible male and female connectors that are electrically engaged by sliding a loose module along a rail and into engagement with modules that are fixed to the rail. The modules are secured to the rail by two manually operated slidable tabs that slide through slots in the housing to engage lateral portions of the rail. To repair or replace a selected module in the stacked arrangement, it is necessary to release the slidable tabs for all the modules to one side of the selected module, then slide and remove all the released modules from the rail before the selected module can be removed, repaired or replaced. The whole process is then repeated to remount all the modules. This process can cause excessive wear on components that may engage the rail as well as take time. It is desirable, therefore, to have a module that can be removed and remounted to a rail without disturbing the other modules on the rail.
U.S. Pat. No. 5,842,889 discloses a module having an unlocking device for a locking fasteners on sides of a rail receiving portion of a module. The device includes a dielectric bracing piece integral with each of the locking fasteners and extending toward the middle of the underside of the module. The inner ends of the bracing pieces are secured to a rod that extends upwardly through the module. The locking feet or clamps on the underside of the module are opened by activating a rod that presses locking feet out of engagement with the rail.
International Patent Application Publication No. WO 97/10692 discloses modules that are mounted to a rail by engaging a first edge of the rail with a lip on one side of a rail receiving recess of the module, pivoting the module about an axis in a direction substantially parallel to the stacking direction and engaging a resilient latch to the other edge of the rail. The module may be removed by prying open the latch and pivoting in the opposite direction.
It is an object of the present invention to provide a spring loaded clamp for a module that automatically secures the module to the rail upon mounting the module in a direction vertical to the longitudinal axis of the rail.
It is a further object to provide a device that can be readily operated to enable removal of the module from the rail in a vertical direction.
The present invention is directed to mounting clamps for mounting modules to a rail that overcomes the problems associated with the prior art. At least two clamps are used for each module. The clamps are spring loaded and can be activated by mounting the module to the rail in a vertical direction without the use of tools. The module includes an actuator that can be operated with a simple tool to effect release of the clamps and removal of the module from the rail. It is to be understood that more than one pair of clamps may be used with a wide module.
A mounting system for electrical modules having a housing with a rail mounting face including a rail receiving recess, and a plurality of electrical terminals disposed therein for electrical engagement with complementary terminals of an adjacent module when in a stacked arrangement. The mounting system includes a pair of spring loaded mounting clamps disposed on the mounting face and movable between a first or latched position and a second or open position. Each clamp includes a body portion having a spring receiving cavity, a base extending outwardly from a lower edge of the body portion in one direction and a rail engaging arm extending outwardly from an upper edge of the body portion and in a direction opposite to the base. The body portion includes a wall extending at an angle from the base to the arm and defining a rail latching surface proximate the arm. The base and arm are movably mounted along respective tracks between the latched and opened positions. A partially compressed spring is disposed in the cavity such that the clamps are normally in the latched position.
The clamps can be moved from the latched to the open position by engagement with the upper surface of a rail whereby the rail moves along the angled walls, acting as a camming surface to exert force against the walls such that the spring compresses until the respective latching surfaces are moved out of the rail receiving recess and the rail engages the rail mounting surface of the housing. Upon the module being fully mounted to the rail force against the walls ceases and the spring expands moving the latching surfaces into engagement under edges of the rail.
The invention further includes a device for opening the clamps and releasing the module from the rail, the device being an actuator defining a camming surface that engages a leading end of both of the clamps such that upon rotating the actuator from a first orientation to a second orientation, force is exerted on the arm ends to cam the arms to the open position thereby permitting removal of the module from the rail. The module may also be mounted to the rail in the open position and the actuator rotated to secure the module to the rail.